Page 472 - Problem-Based Feline Medicine

464 PART 7 SICK CAT WITH SPECIFIC SIGNS

with a severely distended bladder following ure- ● Creatinine or potassium levels in the abdominal
thral obstruction. fluid greater than that of the serum are strongly
● Penetrating abdominal trauma. suggestive of uroperitoneum. (It is not sufficient to
– Bite wounds, staking injuries and bullet wounds simply measure those parameters in the peritoneal
are uncommon causes of urinary tract trauma. fluid because azotemic animals with ascites will
also have creatinine and potassium in the ascitic
Acute bladder rupture occasionally causes marked
fluid.) The higher the abdominal fluid:serum creati-
hemorrhage into the abdomen or into the bladder (with
nine and potassium ratios, the more likely the cat
massive clot formation).
has uroperitoneum. In one study of cats with
uroperitoneum, the abdominal fluid:serum creati-
Clinical signs nine ratio ranged from 1.1:1 to 4:1, with a mean of
2:1, and the abdominal fluid:serum potassium ratio
Clinical signs are due to post-renal uremia and asso-
ranged from 1.2:1 to 2.4:1, with a mean of 1.9:1.
ciated disorders.
Abdominal fluid:serum urea ratios are not as reli-
Non-specific signs of uroperitoneum include variable able because of more rapid equilibration of urea.
depression, lethargy, anorexia and dehydration.
Contrast radiography will demonstrate a rupture of the
Body temperature and heart rate may be elevated, nor-
bladder or urethra. To demonstrate a rupture of the
mal or low. Vomiting is common. Abdominal pain may
bladder, the radiograph should be obtained just as
be present.
the final amount of contrast material is injected. If
Many cats are not urinating, but presence of urination only a small amount of contrast material leaks out of
does not rule out urinary tract rupture. (If urination the bladder, it may be rapidly diluted in the peritoneal
is present, there may be hematuria.) fluid resulting in a false-negative study.
Similarly, a palpable bladder does not rule out rup-
Differential diagnosis
ture of either the bladder or urethra.
Abdominal distention and a fluid wave are occasionally Differential diagnoses for a cat presented for no urina-
evident. Urethral rupture may also cause inguinal sub- tion include ethylene glycol or lily poisoning, or ure-
cutaneous edema (there may also be signs of inflam- thral obstruction.
mation due to cellulitis). Differential diagnoses for a cat presented with acute
depression and peritoneal fluid include right heart
Diagnosis failure, acute pancreatitis, liver disease with ascites
and hepatic encephalopathy, and acute abdominal
A serum chemistry profile will reveal mild to marked hemorrhage (mucous membranes will be pale).
elevations in urea and creatinine levels unless the
animal is tested shortly after injury. Hyperkalemia may Other rare causes of uroperitoneum include spontaneous
also be present. leakage at the site of a bladder tumor, traumatic avulsion of
a ureter, transudation of urine through a severely inflamed
Abdominal ultrasonography will demonstrate peri- bladder wall and leakage post-nephrotomy. Radiographic
toneal fluid. contrast studies will facilitate diagnosis. An excretory uro-
Peritoneal fluid is initially a pale yellow to serosan- gram may be required to demonstrate an avulsed ureter.
guineous transudate, and cytology will be unremark-
able, unless the cat is a tom, where sperm may be Treatment
9
present. Cell counts may increase with time (> 3×10 /L,
Fluid therapy to correct dehydration and reduce uremia.
3000/μl) resulting in a modified transudate. Secondary
septic peritonitis will result in an exudate with degen- Antibiotics if there is secondary septic peritonitis, e.g.
erate neutrophils and bacteria. ampicillin, cefoxitin at standard doses.